This invention relates to permanent magnet direct current electric motors and more particularly to an electric motor having a radially wound armature, space efficient magnets, chokes and brushes, which permit elimination of an outer casing for covering the armature.
Conventional permanent magnet direct current electric motors, particularly for automotive applications, contain an axially-wound rotating armature surrounded by a stationary steel structure that acts as a motor case. The case functions to retain and support the permanent magnets, to provide a conduit for lines of magnetic flux, and to provide a cover for the motor to protect internal parts from damage by external forces or influences.
In applications where axial length is restricted, radially-wound armatures are provided. However, in radially-wound armatures, the typical use of a steel case and the conventional location of the brushes and chokes, disadvantageously add to the cost, weight and axial length of the radially-wound motor.
Accordingly, there is a need to provide a permanent magnet direct current electric motor that is radially wound, includes components in gaps between magnets and requires no steel case covering the armature.
An object of the present invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a direct current motor assembly including a stator assembly having a flux plate and four permanent magnets mounted on the flux plate in a manner to define a generally circular outline and defining first and second pairs of spaces between adjacent magnets. The flux plate defines one end of the motor assembly and defines a magnetic flux path of the motor assembly. A pair of brushes are provided with each brush being disposed in an associated space of the first pair of spaces. A pair of chokes are provided with each choke being disposed in an associated space of the second pair of spaces.
An armature assembly is disposed adjacent to the stator assembly and defines another end of the motor assembly. The armature assembly is radially wound with wire windings, and an outermost part and at least a portion of the wire windings of the armature assembly are exposed to the environment.
In accordance with another aspect of the invention, a motor and fan structure includes a direct current motor assembly having a stator assembly including a flux plate and permanent magnet structure mounted on the flux plate. The flux plate defines one end of the motor assembly and a magnetic flux path of the motor assembly. The motor assembly also includes a generally cylindrical armature assembly defining another end of the motor assembly. The armature assembly is radially wound with wire windings, and an outermost part of the armature assembly and at least a portion of the wire windings are exposed to the environment.
The structure includes a fan having a generally cylindrical hub receiving and covering the exposed outermost part and the portion of the wire windings of the armature assembly. The hub has a plurality of blades extending therefrom. Thus, the weight and axial length of the motor assembly can be reduced since no case is required to cover the armature assembly yet the armature assembly is protected by the fan hub.